Jai Prakash Chaudhary

Chitosan-Based Aerogel Membrane for Robust Oil-in-Water Emulsion Separation.

Here, we demonstrate direct recovery of water from stable emulsion waste using aerogel membrane. Chitosan-based gel was transformed into highly porous aerogel membrane using bio-origin genipin as cross-linking agent. Aerogel membranes were characterized for their morphology using SEM, chemical composition by FTIR and solid-UV. Further, aerogel was tested for recovery of high quality water from oil spill sample collected from ship breaking yard. High quality (with >99% purity) water was recovered with a flux rate of >600 L·m(-2)·h(-1)·bar(-1). After repeated use, aerogel membranes were tested for greener disposal possibilities by biodegrading membrane in soil.

A green and sustainable approach to utilize bio-ionic liquids for the selective precipitation of high purity agarose from an agarophyte extract

A few choline based bio-ionic liquids (bio-ILs) were employed for the first time for the selective precipitation of agarose from the hot seaweed extract of Gracilaria dura (an agarophyte) under ambient conditions. The method thus developed is much “greener” and economical in comparison with the methods widely practiced for agarose production. Among the bio-ILs, choline laurate was found to be the most effective for the isolation of agarose with a lower usage level (4.0%, w/w) with the yield of 14.0 ± 0.5% w/w. Agarose obtained by this process had the desired properties required for molecular biological applications and gel electrophoresis. Furthermore the bio-ILs were recycled and reused for subsequent batches of agarose isolation without compromising the yield and quality of biopolymers.

Surfactant-induced coagulation of agarose from aqueous extract of Gracilaria dura seaweed as an energy-efficient alternative to the conventional freeze–thaw process

Surfactant-induced coagulation of agarose from alkali-treated Gracilaria dura seaweed extract (SE) is reported. The new approach, which was suitable for linear galactans with low sulphate content is an alternative to the traditional energy intensive process of “freeze–thaw” cycles employed for product isolation from the extract. Only nonionic surfactants were effective, and detailed studies were undertaken with octyl phenol ethoxylate (Triton X-100). The coagulated product was successively washed with water and water–isopropyl alcohol (IPA) to yield a fine powder of agarose in 13–15% yield (with respect to dry biomass). The product exhibited excellent properties [sulphate content: 0.2% w/w; degree of electro-endosmosis: 0.13; gel strength: 2200 g cm−2 (1% gel, w/v); and gelling temperature: 35 ± 1 °C] essential for demanding molecular biology applications, and the desired gel electrophoretic separation of DNA and RNA was demonstrated. It was further confirmed that there was no degradation of nucleic acids in the gel. The agarose-depleted extract, along with water used for washings, was subjected to reverse osmosis for recovering the surfactant in concentrated form for its subsequent reuse. Energy savings from the improved process were assessed.

Simultaneous dehydration of biomass-derived sugars to 5-hydroxymethyl furfural (HMF) and reduction of graphene oxide in ethyl lactate: one pot dual chemistry

Low yield of chemicals is often identified as a major obstacle for the complete utilization of bioresources as a source of important chemicals and thereby limits their application in industries. The issue of low yield can be partially compensated by integrated processes, i.e., production of two or more chemicals from the same biomass using single or multistep processes. Herein, a simple pathway for simultaneous production of 5-hydroxymethyl furfural (HMF) from biomass-derived sugars by dehydration of fructose (molar yield 76.3%) using graphene oxide (GO) as acid catalyst and choline chloride (ChoCl) as additive in ethyl lactate is demonstrated. Moreover, during the course of reaction GO was reduced to produce six-layered graphene nanosheets (96% recovery). Furthermore, the solvent was recycled after recovery of both products and successfully reused for subsequent production of the two chemicals with high purity.

Synthesis of bio-based aldehyde from seaweed polysaccharide and its interaction with bovine serum albumin.

Here, we demonstrate a successful synthesis of bio-based aldehyde namely dialdehyde-carboxymethylagarose (DCMA) using carboxymethyagarose (CMA). Further reaction parameters (i.e. reaction temperature, pH and periodate concentration) were optimized to achieve maximum aldehyde content and product yield. The synthesis of DCMA was confirmed by employing FTIR, (1)H NMR, XRD, SEM, AFM, TGA, DSC, EA and GPC techniques. To investigate the aldehyde functionality, DCMA was allowed to interact with BSA and obtained results were found to be comparable with that of synthetic aldehyde (Formaldehyde). Further interaction of DCMA with BSA was confirmed by using UV-vis, FTIR, fluorescent spectroscopy, CD and DLS analysis. Results of this study revealed that bio-based aldehyde behaves like formaldehyde. This study adds value to abundant marine biopolymers and opens the new research area for polymer researchers.

Agarose based multifunctional materials: evaluation of thixotropy, self-healability and stretchability.

This paper reports a microwave assisted one pot facile synthesis of ester derivatives of agarose (Agr-GAEst) through chemical reaction of agarose (Agr) with gallic acid (GA), an organic acid found in many plants employing carbodiimide chemistry. Agr-GAEst was characterised by FT-IR, (13)C NMR spectroscopy, thermogravimetric analysis (TGA), DMA measurements, scanning electron microscopy (SEM), UV-vis spectrophotometry and rheometry. The native agarose was insoluble in ethylene glycol, but Agr-GAEst (obtained at an optimized molar ratio of 1: 0.5) formed good quality gel (tanδ ∼ 0.1) at 4% (w/v) concentration. The gel thus obtained exhibited substantial degree of thixotropy (hysteresis loop area=38.73%), rapid self-healing ability (12 min) upon complete cleavage of the gel and excellent stretching ability (>20 times of its original length). These types of multifunctional gels would find applications in food and personal health care industries.

Carboxymethylagarose-AuNPs generated through green route for selective detection of Hg2+ in aqueous medium with a blue shift

We report here a facile, rapid, cost-effective method via a green route for the selective detection of Hg(2+) in aqueous media. In this study carboxymethylagarose (CMA) is used to generate gold nanoparticles and subsequently to act as a stabilizer for the CMA-functionalized gold nanoparticles (CMA-AuNPs). The resulting CMA-AuNPs was characterized by UV-visible, X-ray diffraction, transmission electron microscopy (TEM), dynamic light scattering (DLS), atomic force microscopy (AFM) and zeta potential measurements. Zeta potential value (∼ -73 mv) of CMA-AuNPs in the aqueous medium shows its higher stability. When CMA-AuNPs were exposed to an aqueous Hg(2+), a blue shift for its localized surface plasmon resonance absorbance (LSPR) band is observed along with significant colour change of the solution. The probe enables to detect Hg(2+) in the range of 0.01-100 ppm even in spiked lake water samples. This study offers a sustainable and eco-friendly route for selective detection of Hg(2+) in aqueous solution and may find potential application towards water purification.